method def in method vs method def in block

[Kyung won Cheon]

class A
def aaa
puts "called aaa by #{self}"
def bbb
puts "called bbb by #{self}"
end
end
end

a = A.new
p a.respond_to?bbb) # => false
a.aaa
p a.respond_to?bbb) # => true
a.bbb

p A.public_instance_methods.grep(/bbb/) # => ["bbb"]

a2 = A.new
a2.bbb

p a.respond_to?ccc) # => false

a.instance_eval do
def ccc
puts "called ccc by #{self}"
end
end

p a.respond_to?ccc) # => true
a.ccc

p A.public_instance_methods.grep(/ccc/) # => []

a2.ccc rescue puts $! # undefined method

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# What's the diff ??
# Help Me^^
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